Current-collecting device.



'1. s. DEAN.

CURRENT COLLECTING DEVICE.

APPLICATION FILED JUNE 4. 1915.

PatentedSept. 3, 1918.

INVENTOR John 5 Dean.

-ATTORNEY "4E NORRIS PETERS CO.- PNGTOLITNO. WASNINz'mIL D. C.

UNITED STATES PATENT OFFICE.

JOHN S. DEAN, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSEELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN SYLVANIA;

YCURRENT-COLLECT ING DEVICE.

- Specification of Letters Patent.

Patented Sept. 3, 1918.

Application filed June 4, 1915. Serial No.32,210.

To all whom it may concern:

Be it known that I, JOHN S. DEAN, a citizen of the United States, and aresident of VVilkinsburg, in the county of v Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Current-Collecting Devices, of which the following is a specification.

' My invention relates to current-collecting devices for dynamo-electricmachines, and it has for its object to provide an improved structure foruse in connection with devices of the above-indicated character wherebycertain operating difficulties which have been experienced in the priorart shall be obviated. I

Current-collecting devices, as heretofore constructed, have usuallyconsisted of a current-collecting member or brush adapted to be inengagement with a rotatable commutator cylinder or othercurrent-delivering surface and supported by means of a suitable bodymember or brush holder. The brush is usually held in operative relationwith respect to the coacting rotatable member by means of apressure-exerting member carried by the brush holder and engaging thebrush. I I

It is well known that the current-carrying capacity of a brush holder isdetermined by the amount of current that the brush-holder body cantransmit from the brush without excessive heating. For this reason, ithas been customary to employ a current-carrying member of highconductivity connected in parallel circuit relation-with respect to thebrush-holder body and the brush. Such a conductor or shunt serves todivide the current taken to or from the brush and thereby materiallyreduces the heating of the brush-holder body. Heretofore, considerabledifliculty has been encountered in securing a satisfactory electricalconnection between theshunt and the brushby reason of the inherentmechanical properties of the usual brush material and the movements ofthe brush within the brush box. 'The shunts have been usually secured tothe brush by rivets or by suitable metallic connecting members but suchdevices have proved un satisfactory, as they are liable to becomeloosened and cause the brush holder to carry the total current, withresultant overheataccording to the present invention, I

provide a conducting member that is particularly adapted for use as ashunt in con nection with carbon or metal-carbon brushes. 1

A shunt constructed in accordance with my invention is adapted to beinterposed between the brush and the pressureexerting means whicharrangement insures that the shunt will retain its electrical connectionwith the brush as long as the brush holder remains in operativecondition.

In the accompanying drawings, Figure 1 is a view, partially in sideelevation and partially insection, of a current-collecting deviceembodying my invention; Fig. 2 is a plan view of a portion of thestructure shown in Fig. 1; Fig. 3 is a view,in front elevation, of aportion of the parts shown in Fig.1, and Figs, 4 and 5 are fragmentaryviews showing a modification of my invention. I v The brush holder shownin the drawings a. copending application, Serial No. 848,848,

is similar tothe brush holder described in I filed July 3, 1914, nowPatent 1,244,476,

issued Oct. 30, 1917, by me and assigned to the Westinghouse Electric &Manufacturing Company. I

The current-collecting device comprises a suitable current-collectingmember or brush 1 that is in engagement with a commutator cylinder 2 ofa dynamo-electric machine and is adapted to slide within a guidingaper-' ture or brush box 3. The brush box 3 is disposed at one end of abrush holder frame 4 and the latter is provided with an upwardlyextending member 5 that is adapted to be secured to the frame of thedynamo-electric machine, (not shown) by a suitable clamping device. Thebrush holder 4 is further provided with a spring means 6 that is securedto the frame by suitable retaining means 7 and comprises a plurality ofconvolutions 8 of resilient material, the end of the innermost turnbeingsecured to acentrally located sleeve member 9. The sleeve 9 extendsthrough the coil 8 and is connected to a yoke member 10 through asuitable ratchet-andpawl mechanism 11, shown in dotted lines, the yokemember 10 thus being movable with the coil 8. The bridge portion 12 ofthe yoke member 10 is provided with a projecting arm or finger 13 and aprotecting shield member 14. The finger13, preferably formed of flatspring material, extends outwardly and adjacent to the brush means, suchas a rivet 17, and terminates. in.

a contact tip 18. The contact tip 18 comprises a flat plate 19,"preferably composed of pure copper or other similar material having ahigh electrical conductivity, and apressure plate 20, preferablycomposed of steel or other similar materialhavinga relatively lowelectrical conductivity. The end portion of the shunt 16 is disposedbetween the plates 19 and. 20. and the several members are securedtogether to form a substantially unitary structure by welding, brazingor otherwise. The pressure plate 20 is formed with. a pair ofoppositelydisposed bent-over cars 21- that are adapted to embrace the cylindricalportion 15 of the spring member 13, as best shown in Fig; 3. Thereissufficient clearancebetween theears 21 and spring 13 to preventwedgingbetween the members, In Figs. 4 and 5 is shown a modification ofthe construction of the contact tip 18 of the shunt-16, wherein thepressure plate 2 0 is. formed'with a sub stantially cylindrically curvedportion 22. The cylindrically curved portion 22 is dis-. posed with theaxis thereof at right.- angles to'the axis of the semi-cylindricalportion 15 of. thespring 13,v as best shown in Fig. 5. This arrangementallows a substantially uni.- versal movement between. the coactingcylindrically curved surfaces 15. and 22 sothat the full pressure of thespringmeans 6-.will always be applied to the plate 21' at a sin 'lepoint on the surface thereoffor any position of the brush 1 within thebrush b021 3.

From theforegoing, it is apparent that a shunt provided witha contacttip constructed inaccordance withuny invention will al ways secure goodelectrical contact between the brushand the shunt, so long as thepressure-exerting means maintains its operative relation to the brush.The steel pressure plate provides a good wearing surfaceforthecylindrically curved portion of the spring.,and.the relatively highresistance of this plate, in comparison with the copper contact plate,insures that only a negligible amount of current will pass through. thespring. Overheating of. the spring is there:

. by eii'ectively prevented and it will therefore. even.

retain its, tempen and. resiliency, though the brush holder be.subjected to. heavy overloads.

lVhile I have shownmy invention, in a simple and preferred form and asapplied to a, certain, type of brush holder, it is. apparent thatit,maybe applied to any other type ofcurrentecollecting device andisisubject to. only such-limitations as may come within the scopeof-theappendc(l claims.-.

I claim as my invention:

1. The combination with a brush holder, a brush carried thereby, andaspring for applying pressure to the said brush, oi.- current-carryingmeans connected, at one end, to the said" brush holder and provided, atthe other end, with a plate in contact with thesaid brush, and apressure plate having portions. embracing the said spring.

2. The combination with a brush holder, a brush carried thereby,. andaspring for applying pressure to the. said brush of an independentlyremovable current carrying means interposed. between the said brushandthe said" spring and. comprising a plate in contactwiththe said.brush,aflexible con? ductor connected to the said brush: holder and a pressureplate provided with. projecs. tions embracing thefend portion of saidspring,

3. The combination with a, brush holder, a brush carried thereby, and aspring for applying pressure to the said brush, the said springterminating in: a semi cylindrical portion, of a current ca-rrying meansinterposed between the said brush and the said Springand provided with apressure plate having a cylindrically curved portion the axisofwhichisat right anglesto the axis of. the semi-cylindrical portion of thesaid spring y v i 4. The combination with a current-collectingmembenaholding membertherefor, and means for applying pressure to thesaidcurrent-collecting. member, of a current-canryingmeans interposedbetween the said ourrentrcollectingmember and the said pres sureapplying means, the said current-carrying means and the said pressure:applying means being provided with coacting cylindricallycurvedsurfaces, the axes of which are disposed at right angles to eachother. 5. The combination with abrush holder,

a brush. carried thereby, a current-carrying. means connected at one endto sald'brush holder and at the other end to saidbrush, and a spring,adaptedto exert pressure on. said brush, of a plate of relatively lowresistivity interposed between said currentcarrying means and said'brushand a plate of relatively. higher resistivity interposed be.- tween saidcurrentwarryingmeans and said spring. a. i

6. Thecon'ibination. with a brush holder, a brush carried thereby and aspring adapted to exert pressureon said brush, of a flexible conductorhaving one end connected to saidbrushholder and the other end in.-

serted between said spring and said brush, a.

contact platecomposed of a metalof relatively high conductanceinterposed between said brush, and. said flexible conductor, and. apressure plate composed of a material of.

relatively low conductance, said contact plate, said pressure plate andsaid flexible conductor being united to form a unitary structure.

7. The combination with a brush holder, a brush carried thereby and aspring adapted to exert pressure on said brush, of a flexible conductorhaving one end connected to said brush holder and having the other endinserted between said brush and said spring, a copper contact plateinterposed between said flexible conductor and said brush, and a steelplate interposed between said spring and said flexible conductor, saidcopper plate, said flexible conductor and said steel plate being unitedto form a unitary structure. V

In testimony whereof I have hereunto subscribed my name this 26th day ofMay, 1915.

JOHN S. DEAN.

coplel of thin potent may be obtained for five cents each, by addressingthe Commissioner of Potato,

Wuhlngton, D. 0.

